1. Field of the Invention
The present invention relates to a method for driving a plasma display panel in a matrix display scheme.
2. Description of Related Art
In recent years, a plasma display panel (hereinafter referred to as the xe2x80x9cPDPxe2x80x9d), an electroluminescent display panel (hereinafter referred to as the xe2x80x9cELDPxe2x80x9d) and so on have been brought into practical use as thin flat display panels of matrix display scheme. These PDP and ELDP have pixel cells, which function as pixels respectively, arranged in the form of a matrix comprised of n rows and m columns. The pixel cells have only two states: xe2x80x9clight emissionxe2x80x9d and xe2x80x9cnon-light emission.xe2x80x9d Therefore, gradation driving based on a subfield method is conducted for a display panel such as the above-mentioned PDP and ELDP to provide a halftone luminance level corresponding to an input video signal.
The subfield method involves converting an input video signal into N-bit pixel data pixel by pixel. One field display period in the input video signal is constituted by N subfields each of which corresponds to each of N bit digits. A number of light emissions corresponding to each bit digit in the pixel data, is allocated to each of the subfields respectively. When a bit digit in the N bit is, for example, at logical level xe2x80x9c1,xe2x80x9d light is emitted the number of times allocated as mentioned above in a subfield corresponding to the bit digit. On the other hand, when the bit digit is at logical level xe2x80x9c0,xe2x80x9d no light is emitted in the subfield corresponding to the bit digit. The driving process using the subfield method stepwisely represents a halftone luminance level corresponding to an input video signal by a total number of light emissions which are performed in each of subfields within one field display period.
It is an object of the present invention to provide a display panel driving method which realizes a good gradation display corresponding to an input video signal.
The present invention provides a display panel driving method for driving a display panel having a plurality of pixel cells arranged in matrix in accordance with a video signal. A unit display period in the video signal is constituted by a plurality of divisional display periods. In each of the divisional display periods, a pixel data writing stage is performed for setting each of the pixel cells to either a light emitting cell or a non-light emitting cell in accordance with pixel data corresponding to the video signal, and a light emission sustain stage is performed for causing only the light emitting cells to emit light a number of light emissions allocated thereto corresponding to a weighting factor applied to each of the divisional display periods. A luminance distribution of the video signal is measured every display line on the display panel, and the number of the divisional display periods in the unit display period is changed in accordance with the luminance distribution every display line.